In recent years, a significant industry has developed which involves the application of customer-selected designs, messages, illustrations, and the like (referred to collectively hereinafter as “customer-selected graphics”) on articles of clothing, such as T-shirts, sweat shirts, and the like. These customer-selected graphics typically are commercially available products tailored for a specific end-use and are printed on a release or transfer paper. The graphics are transferred to the article of clothing by means of heat and pressure, after which the release or transfer paper is removed.
Heat transfer papers having an enhanced receptivity for images made by wax-based crayons, thermal printer ribbons, ink-jet printers, impact ribbon or dot-matrix printers, are well known in the art. Typically, a heat transfer material comprises a cellulosic base sheet and an image-receptive coating on a surface of the base sheet. The image-receptive coating usually contains one or more film-forming polymeric binders, as well as, other additives to improve the transferability and printability of the coating. Other heat transfer materials comprise a cellulosic base sheet and an image-receptive coating, wherein the image-receptive coating is formed by melt extrusion or by laminating a film to the base sheet. The surface of the coating or film may then be roughened by, for example, passing the coated base sheet through an embossing roll.
Much effort has been directed at generally improving the transferability of an image-bearing laminate (coating) to a substrate. For example, an improved cold-peelable heat transfer material has been described in U.S. Pat. No. 5,798,179, which allows removal of the base sheet immediately after transfer of the image-bearing laminate (“hot peelable heat transfer material”) or some time thereafter when the laminate has cooled (“cold peelable heat transfer material”). Moreover, additional effort has been directed to improving the crack resistance and washability of the transferred laminate. The transferred laminate must be able to withstand multiple wash cycles and normal “wear and tear” without cracking or fading.
Various techniques have been used in an attempt to improve the overall quality of the transferred laminate and the article of clothing containing the same. For example, plasticizers and coating additives have been added to coatings of heat transfer materials to improve the crack resistance and washability of image-bearing laminates on articles of clothing. However, cracking and fading of the transferred image-bearing coating continues to be a problem in the art of heat transfer coatings.
One of the problems with conventional heat transfer materials occurs when attempting to transfer materials to a dark substrate. When transferring material to a dark substrate, an opaque light colored or white background is often required. When conventional heat transfer materials and processes are used, opacity and whiteness are lost. The images have a washed out appearance of the layer they are printed on, since the image penetrates into either the opaque layer or the fabric. Another problem with conventional heat transfer materials occurs with cracking of the image after transfer of the image. This cracking results after normal washing of the substrate and printed image due to normal stretching of the fabric as the image layer is a continuous film on the surface of a bendable, stretchable fabric.
What is needed in the art is a heat transfer material, which can be transferred to dark material while maintaining brightness and minimal fading even after extensive washing. If a white or light colored opaque coating is used in the heat transfer material, the opaque coating should be maintained after extensive washing. Also, what is needed is a heat transfer material that can be transferred to a material while not cracking and breaking apart even after extensive washing. Finally, what is needed is a heat transfer material that has increased breathability and drapability such that the material is more comfortable and softer to wear.